` Delta ABC` में , a= 2 , b= ` sqrt(6)` और ` c = sqrt(3) + 1 , ` तो ` angle A` का मान ज्ञात कीजिए ।

Explanation

` cos A = (b^(2) +c^(2)-a^(2))/(2bc)`
` = ((sqrt(6))^(2) + (sqrt(3) + 1)^(2) -2^(2))/(2 sqrt((6))(sqrt(3)+1))`
` = (2 sqrt(3) ( sqrt(3)+1))/(2 sqrt(6)(sqrt(3)+1 ))=1/(sqrt(2))= cos 45^(@)`
`rArr A = 45^(@)`